How to implement OSD overlay in Wayland/Weston

[Guillermo Rodriguez]

Hi Daniel,

El mar., 19 nov. 2019 a las 13:44, Daniel Stone
(<daniel at fooishbar.org>) escribió:
>
> Hi,
>
> On Tue, 19 Nov 2019 at 11:48, Guillermo Rodriguez
> <guillerodriguez.dev at gmail.com> wrote:
> > El mar., 19 nov. 2019 a las 11:47, Pekka Paalanen (<ppaalanen at gmail.com>) escribió:
> > > If the OSD is just a piece of a bigger application and only needs to be
> > > on top of that application's windows, you could probably use xdg
> > > extensions or a sub-surface to realize it. This does mean that the OSD
> > > component must be in-process with the main app and share the same
> > > wl_display instance.
> >
> > The OSD is conceptually part of the fullscreen application but due to
> > several reasons it is implemented as a separate process with a CLI
> > that controls the OSD contents and PiP function; the main application
> > communicates with the OSD process by writing commands to the OSD
> > process' stdin, and reading responses from the OSD process' stdout.
> >
> > There are several reasons for this approach, but the main one is that
> > if there are any issues in the GStreamer side this should not crash
> > the whole application. With the current approach, the main application
> > can just respawn the OSD process if it dies.
> >
> > > I think this should be possible also with GStreamer.
> >
> > Not in the current implementation of the waylandsink plugin -- it
> > always creates its own top level window
> > (https://gstreamer.freedesktop.org/documentation/waylandsink/index.html?gi-language=c),
> > and does not support drawing to an existing surface. But this could be
> > patched if needed.
>
> It is completely possible, using the GstVideoOverlay API. See
> gst-plugins-bad/tests/examples/waylandsink/main.c for an example of
> providing your own wl_surface.

Nice. I assumed this was not possible as the documentation I linked
explicitly states that the waylandsink creates its own window.
This will definitely make my life easier :-)

Thanks for the pointer,

Guillermo Rodriguez